/Engine/Source/Runtime/Core/Public/HAL/ThreadSafeCounter64.h
If the counter in the Other parameter is changing from other threads, there are no guarantees as to which values you will get up to the caller to not care, synchronize or other way to make those guarantees.
FThreadSafeCounter64 ( const [FThreadSafeCounter64](API\Runtime\Core\HAL\FThreadSafeCounter64) & Other )